The objective of this proposal is to evaluate a new technique of estimating urethral flow resistance which can identify obstructive segments within the urinary outflow tract. Previous measurements of urethral resistance have demonstrated an increase in total outflow resistance due to obstructive lesions such as benign prostatic hypertrophy. However, prior investigators have been unable to demonstrate the obstructive effect of any particular anatomic segment of the outflow tract. Thus, urethral resistance measurements have not been particularly useful as a therapeutic guide. Our proposed technique involves the measurement of intraurethral fluid energy loss during micturition by means of a pressure microtransducer mounted at the tip of a 7 French ureteral catheter with its pressure sensing diaphragm oriented perpendicula to the urinary steam in order to monitor both the static and kinetic components of fluid energy (total fluid pressure). Under barbiturate anesthesia, thirty female mongrel dogs will have a suprapubic 18 French double lumen catheter placed in the urinary bladder. The pelvic nerves will be electrically stimulated bilaterally to induce detrusor muscle contraction. In the control group of animals, the microtransducer will be placed in the external stream during steady flow to measure energy loss across the entire undisturbed urethra. In the experimental groups, the microtransducer catheter will be passed into the baldder per urethra prior to pelvic nerve stimulation and withdrawn at a known rate during voiding until it lies in the external urinary stream. In further experiments, local urethral resistance will be altered by intravenous norepinephrine, phentolamine, pudendal nerve section, pudendal nerve stimulation and combinations thereof. The experimental protocol is designed to continously monitor the fluid energy loss occurring within the urethra during micturition and allows determination of the contribution of any given urethral segment to the total urethral resistance. Our overall objective is to develop a technique, currently nonexistent, capable of localizing obstruction within the urethra which may be used for diagnostic study of the human lower urinary tract.